The invention pertains generally to a means for providing compressed gas. Such gas is required in the context of a number of different types of processes and operations, for example for various oil well service operations. For many such operations, the gas should be substantially inert. At present, such gas is often obtained from liquified nitrogen. However, transportation of liquified nitrogen can be a problem in certain geographical areas.
In the past, it has also been known that inert gases can be obtained from the exhaust from various types of engines. For example, U.S. Pat. Nos. 3,000,707, 3,522,846, 3,833,059 and 3,232,885 all generally pertain to such methods. However, the conventional practice has been to obtain such gas from the exhaust output of the engine, i.e. at atmospheric pressure, and then recompress it to the required pressure for its intended use. This general method requires compressors which are not only expensive per se, but are also expensive to operate.